The finding supports the hypothesis that the balls "were involved in kitchen activities related to food processing," archaeologists Stephanie Simms, Francesco Berna, of Boston University, MA, and George Bey of Millsaps College, MS, wrote in the Journal of Archaeological Science.

"This is the first time fired clay balls have been studied in the Maya area and, to my knowledge, no one has documented the use of clay balls in modern Maya cooking," Simms told Discovery News.

Located in the Puuc Maya hills of Yucatán, Escalera al Cielo was an elite residential settlement that was rapidly abandoned sometime near the end of the Terminal Classic period (800-950 A.D.), as shown by ceramic vessels, stone tools, personal adornments, and other materil assembled on the floors.

"We know much about the nature of ancient Maya kings and queens, but this type of study helps see how the Maya worked in the kitchen, what kinds of tools they used and the ways they might have prepared their cuisine," Bey, the project co-director along with archaeologist Tomás Gallareta Negrón and anthropologist William Ringle, told Discovery News.

To better understand the meaning of the fired clay balls, the researchers used a suite of microscopic techniques and experimental replication. The tests revealed that the balls were produced from local clay in a standardized set of sizes.

"They were fired at a fairly low temperature and were used repeatedly in the kitchen," Bey said.

Most likely, the fired clay balls were either placed directly into pots of food to cook or heat it, or used in pit (pib in Mayan) oven cooking installations.

"This cooking method involves digging a shallow pit, lining it with stones or clay balls, building a fire on top and waiting until it is reduced to embers," Simms said.

The process continued by placing whole roots, squash fruits or packets of food wrapped in maize on the hot stones. Everything was then covered with earth and leaves to seal in heat. Cooking took from one hour to up to a day or more.

The experimental tests showed "how the ancient Puuc Maya manipulated materials available to them to produce objects that potentially represent a staple of every Puuc Maya kitchen inventory, maybe even representing a local cooking technique and cuisine," Simms said.

Fired clay balls have been described from a variety of archaeological contexts worldwide, particularly in the Lower Mississippi River Basin and southeastern United States, and in areas of southwest Asia where clay is abundant but stone are not. Similar clay balls were also unearthed in the neolithic village of Catalhoyuk in Turkey, where they were found in hearths and interpreted as cooking or heating implements.

Charles Kolb, an anthropologist, archaeologist and senior program officer in the Division of Preservation and Access at the National Endowment for the Humanities, Washington DC, agrees that Bey and colleagues "have provided logical inferences of artifact use."

"The fired clay balls show multiple heating episodes rather than just one firing. A single firing might suggest the use as these balls as 'sling stones' or offensive weaponry, but their size would connote other uses," Kolb told Discovery News.

"The multiple firings of these balls points to uses in culinary activities with these fired clay balls substituting for stones," he added.